Nuclear implant apparatus and method following partial nuclectomy

ABSTRACT

An expandable implant for augmenting a damaged or otherwise torn posterior annulus fibrosus. The implant is deployable into an evacuated posterior disc space following a subtotal nuclectomy. The implant includes an inflatable balloon which is fixed to the annulus fibrosus to protect against migration. When inflated with a curable polymer, the posterior wall of the implant is intimately disposed along the inner surface of the annulus fibrosus to provide a substantially fluid-tight seal of the annular tear or defect and reinforce the weakened posterior annulus. The anterior wall of the implant sequesters the nuclear remnant to guard against disc remnant herniation. The implant can restore intradiscal pressure and disc height. An integrated posterior reinforcement band creates a strong, yet flexible and resilient structure, resistant to penetration of the implant through the annular tear or defect.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/934,987 filed Nov. 6, 2015. The entire contents of theabove-referenced disclosure is specifically incorporated by referenceherein without disclaimer.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to spinal surgery and moreparticularly to a method and apparatus for reinforcing a torn or damagedannulus fibrosus.

DESCRIPTION OF RELATED ART

Spinal discs typically have an intact annulus fibrosus throughout lifethat confers normal resistance to applied forces. Degenerating discs,however, exhibit mechanical failure of the disc. A common mechanicalfailure is radial tears in the annulus fibrosus.

Radial tears of the annulus fibrosus are characteristic of alldegenerating intervertebral discs and are often associated with loss ofdisc height, segmental instability and pain. By definition, a radialtear is a defect that extends through all layers of the annulusfibrosus, from its interior margin to the periphery of the disc.

Radial tears are found most commonly in the lumbar spine and are mostprevalent at the L4-L5 and L5-S1, disc levels. Most radial tears involvethe posterior annulus and occur without disc herniation, even inpatients with clinical findings typical of a herniated disc. In thelumbar region, pain is often referred to a lower extremity. The referredpain may be difficult to distinguish clinically from radiculopathy of aherniated nucleus pulposus compressing a spinal nerve.

Breakdown of the nucleus pulposus generates fluids and tissues that mayleak outward through the radial tear, causing inflammation of adjacentmeninges and innervated granulation tissue along the radial tear.

The disruption of the annulus fibers by a radial tear is associated withloss of intradiscal pressure and disc height resulting in hypermobilityor instability of the motion segment at the level of the affected disc.It is postulated that the spinal instability permitted by a radial tearmay cause pain by straining the facet joints and connective tissues thatextend across the degenerating disc.

The associated increased mobility may produce intermittent nerve rootcompression at spinal levels containing a radial tear. Intermittentoccult spinal stenosis, lateral recess stenosis and neural foraminalstenosis may occur during changes in posture and physiologic loading ofthe spine.

Functional tests such as discography may demonstrate radial tears atmultiple levels and identification of the symptomatic radial tear may bedifficult to identify. The value of discography for identifying thesymptomatic disc level and for predicting the outcome from spinal fusionhas been debated.

Physicians sometimes make iatrogenic holes or annulotomies in varioussizes and shapes and locations into the annulus as part of surgicalprocedures to address contained disc herniation or symptomatic radialtears.

In recent years, there has been increasing interest in repair,regeneration and support of the torn annulus fibrosus to restore thenormal function of the disc. There is also interest in repairing radialtears or postsurgical annular defects to prevent recurrence of discherniations and to slow the degenerative process after nuclectomy, inthe context of successful treatment of different types of painful spinalconditions.

Annular repair, whether biologic or surgical, is a developing technologyto address symptomatic annular tears, with or without disc herniations,or in surgical treatments of spinal conditions.

A number of surgical techniques and implants are currently underdevelopment and additional clinical data are expected in the nextseveral years. Absorbable gelatin sponge (i.e., gel foam) appears tohave promise. However, clinical testing has only been done on small sizedefects, and it is difficult to extrapolate this model to a nuclectomy.Sutures with anchors (for example, Xclose and Inclose, AnulexTechnologies, Inc., Minnetonka, Minn.) have been introduced commerciallyand are currently undergoing a U.S. Food and Drug Administration (FDA)trial. Barricaid (Intrinsic Therapeutics, Inc., Woburn, Mass.) is acommercially available implant that anchors into the vertebral body andsupports a woven mesh barrier inserted into the defect.

In an effort to reduce tissue damage associated with surgicalintervention, there is a need to utilize minimally invasive surgicalaccess or percutaneous access. In younger patients with an annular tearor disc herniation who have an otherwise undamaged or minimallydegenerated annulus fibrosus and nucleus pulposus, a partial or targetednuclectomy may be preferable to a total nuclectomy.

Current surgical procedure approaches, access and tools limit thesurgeon's ability to determine the position, size and shape of thecleared disc space. This lack of precision presents difficulty indesigning, sizing, placement and securement of a nuclear implant.Improper nuclear implant placement may interfere with biomechanicalbehavior of the spinal segment. This also increases the likelihood ofmigration and expulsion of the implant.

In sum, an annular tear or defect is clinically significant and requirestreatment. However, commercially available treatments for an annulartear or other damage to an annulus fibrosus have many problems and/ordisadvantages. Various embodiments of the present disclosure maymitigate or solve one or more of the problems and/or disadvantages.

SUMMARY

According to an exemplary aspect of the present disclosure, an apparatusfor reinforcing a damaged annulus fibrosus comprises an inflatableballoon having a first end and a second end, wherein a posterior portionof the inflatable balloon is adapted to seal against an annulusfibrosus; a first anchor coupled to the first end of the inflatableballoon, the first anchor being adapted to anchor the first end of theinflatable balloon to a first location of the annulus fibrosus at afirst lateral side of the annulus fibrosus; and a second anchor coupledto the second end of the inflatable balloon, the second anchor beingadapted to anchor the second end of the inflatable balloon to a secondlateral side of the annulus fibrosus.

The posterior portion of the inflatable implant may comprise areinforcing layer coupled to a posterior side of the balloon so that theposterior portion is substantially non-compliant, and an anteriorportion of the balloon may comprise a silicone material so that theanterior portion is substantially compliant.

The inflatable balloon may comprise any elastomeric biocompatiblematerial suitable for long-term human implantation, such as silicone orPTFE. The inflatable balloon may comprise an electrospun polymericmaterial. The inflatable balloon may further comprise a carbon layerdisposed on an inner surface of the inflatable balloon. The PTFEmaterial may be porous.

The first anchor may comprise at least one inflation port for injectingan inflation material into the inflatable balloon.

The second anchor may further comprise at least one inflation port forinjecting an inflation material into the inflatable balloon.

A curable material may be disposed in the inflatable balloon. A gas maybe disposed in the inflatable balloon.

The inflatable balloon may comprise an anterior portion with differentproperties than the posterior portion. The posterior portion may be lesscompliant than the anterior portion. The posterior portion may comprisemultiple layers.

The inflatable balloon may comprise multiple layers. The multiple layersmay be adapted to provide different properties to the inflatableballoon.

An outer layer of the posterior portion may comprises an opening forallowing an inner layer of the posterior portion to protrudetherethrough upon inflation.

The first anchor may comprise an expanded portion for preventing thefirst anchor from being pulled through the annulus fibrosus therebymitigating against migration or expulsion.

The second anchor may comprise a retaining member with an expandedportion for helping to prevent the second anchor from being pulledthrough the annulus fibrosus. The retaining member may comprise aretaining ring with at least one opening for slidably receiving aslidable plate with at least one aperture for retaining a stringextending from the second anchor.

The inflatable balloon may comprises multiple layers. The multiplelayers may be adapted to provide different properties to the inflatableballoon.

The inflatable balloon may comprise a first chamber and a second chamberdisposed entirely within the first chamber.

The second anchor may comprise first and second loops of materialextending from the second anchor. A retaining member for engaging one ofthe first and second loops of material may be provided.

According to another exemplary aspect, the present disclosure isdirected to a method of reinforcing the posterior of an annulusfibrosus, comprising inserting first and second cannulas through firstand second annulotomies located on first and second sides of theposterior of an annulus fibrosus to gain access to a nuclear disc space;performing a subtotal nuclectomy to create a cavity extending betweenthe first and second cannula, wherein a posterior side of the cavity isformed by the annulus fibrosus and the anterior side of the cavity isformed by a nuclear remnant; inserting an inflatable implant into thecavity formed by the subtotal nuclectomy so that a first end of theimplant is located at the first annulotomy and a second end of theimplant is located at the second annulotomy; inflating the implant witha curable medium so that implant substantially fills the cavity andpresses against the annulus fibrosus to form a substantially fluid tightseal with the annulus fibrosus; anchoring the first end of the implantto the first annulotomy; and anchoring the second end of the implant tothe second annulotomy.

The posterior portion of the annulus fibrosus may have a defect, and thefirst and second annulotomies may be spaced away from the defect onfirst and second sides of the defect.

The first and second annulotomies may be located on the posterolateralsides of the annulus fibrosus.

The steps of anchoring the first and second ends of the implant to thefirst and second annulutomies may comprise removing the first and secondcannulas so that the first and second annulotomies engage the first andsecond ends of the implant.

The step of inserting the inflatable implant into the cavity maycomprise deploying the implant into the cavity through the first cannulaand may further comprise snaring the end of the implant through thesecond cannula and maneuvering the balloon into position.

The step of anchoring the second end of the implant may compriseattaching a retaining member to the second end of the implant, whereinthe retaining member is larger than the second annulotomy.

The step of expanding the implant may further comprise inflating aninterior chamber with a gaseous medium.

According to another exemplary aspect, the present disclosure isdirected to a method of reinforcing a posterior annulus fibrosuscomprises accessing a nuclear space formed by the annulus fibrosus;performing a partial nuclectomy to create a cavity extending from afirst lateral side of the annulus to a second lateral side of theannulus, wherein a posterior side of the cavity is formed by an innerwall of the annulus fibrosus and an anterior side of the cavity isformed by a nucleus remnant; inserting an inflatable balloon with afirst end and a second end into the cavity formed by the partialnuclectomy; inflating the inflatable balloon with a curable medium;anchoring the first end of the inflatable balloon to the annulusfibrosus on the first lateral side of the annulus fibrosus; andanchoring the second end of the inflatable balloon to the annulusfibrosus on the second lateral side of the annulus fibrosus.

The step of accessing the nuclear space may comprise obtaining bilateralposterolateral percutaneous access with first and second cannulas at thefirst and second sides of the annulus fibrosus.

The inflatable balloon may extends from the first cannula to the secondcannula.

The method may further comprise withdrawing the first and secondcannulas, so that first and second annulotomies engage the first andsecond ends of the balloon to anchor the first and second ends of theballoon to the annulus fibrosus.

The inflatable balloon may be deployed through the first cannula intothe cavity. The balloon may be snared through the second cannula andmaneuvered into position.

A portion of the inflatable balloon which is adapted to protrude fromthe inflatable balloon may be aligned with an annular defect, and theinflatable balloon may be inflated so that the balloon protrudes intothe annular defect. The annular defect may comprise a defect caused byone of a herniated nucleus pulposus or an iatrogenic defect.

The balloon may form a substantially fluid tight seal with the annulusfibrosus.

The balloon may substantially prevent leakage of fluids out of theposterior of the annulus fibrosus.

In another aspect of the present disclosure, an anchor for anchoring anuclear implant to an annulus fibrosus through an annulotomy maycomprise an anchor member sized to fit through the annulotomy; at leastone loop of material extending from the anchor member; and a retainingmember with an aperture for receiving and engaging the at least one loopof material, the retaining member being larger than the annulotomy.

The retaining member may comprise a retaining ring and at least onemovable member which is movable between an open position and a closedposition, wherein the movable member has an opening for receiving the atleast one loop of material so that loop of material is movable when theplate is in an open position and immovable when the plate is in a closedposition.

The at least one loop of material may comprise an anchor loop. The atleast one loop of material may further comprise a second loop ofmaterial for allowing a user to snare the second loop of material.

The term “coupled” is defined as connected, although not necessarilydirectly. The terms “a” and “an” are defined as one or more unless thisdisclosure explicitly requires otherwise. The terms “substantially,”“approximately,” and “about” are defined as largely but not necessarilywholly what is specified (and includes what is specified; e.g.,substantially 90 degrees includes 90 degrees and substantially parallelincludes parallel), as understood by a person of ordinary skill in theart. In any disclosed embodiment, the terms “substantially,”“approximately,” and “about” may be substituted with “within [apercentage] of” what is specified, where the percentage includes 0.1, 1,5, and 10 percent.

The terms “comprise” (and any form of comprise, such as “comprises” and“comprising”), “have” (and any form of have, such as “has” and“having”), “include” (and any form of include, such as “includes” and“including”) and “contain” (and any form of contain, such as “contains”and “containing”) are open-ended linking verbs. As a result, a system,or a component of a system, that “comprises,” “has,” “includes” or“contains” one or more elements or features possesses those one or moreelements or features, but is not limited to possessing only thoseelements or features. Likewise, a method that “comprises,” “has,”“includes” or “contains” one or more steps possesses those one or moresteps, but is not limited to possessing only those one or more steps.Additionally, terms such as “first” and “second” are used only todifferentiate structures or features, and not to limit the differentstructures or features to a particular order.

A device, system, or component of either that is configured in a certainway is configured in at least that way, but it can also be configured inother ways than those specifically described.

Any embodiment of any of the systems and methods can consist of orconsist essentially of—rather than comprise/include/contain/have—any ofthe described elements, features, and/or steps. Thus, in any of theclaims, the term “consisting of” or “consisting essentially of” can besubstituted for any of the open-ended linking verbs recited above, inorder to change the scope of a given claim from what it would otherwisebe using the open-ended linking verb.

The feature or features of one embodiment may be applied to otherembodiments, even though not described or illustrated, unless expresslyprohibited by this disclosure or the nature of the embodiments.

Details associated with the embodiments described above and others arepresented below.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view of an annulus fibrosus with a defect and adisc herniation;

FIG. 2 is a sectional view of the annulus fibrosus of FIG. 1 with thedisc herniation removed;

FIG. 3 is a sectional view of the annulus fibrosus of FIGS. 1 and 2 witha posterior portion of the disc removed to form a cavity for receivingan implant;

FIG. 4 is a sectional view of a step in delivering an implant into thedisc space for receiving an implant;

FIG. 5 is a sectional view of another step in delivering an implant intothe disc space for receiving an implant;

FIG. 6 is a sectional view of an implant after insertion;

FIG. 7 is a sectional view of an implant loaded into a delivery cannula;

FIG. 8 is a sectional view of an anchoring mechanism for anchoring theimplant of FIG. 4;

FIG. 9 is a sectional view of the anchoring mechanism of FIG. 8, in acompressed position in the delivery cannula;

FIG. 10 is a sectional view of another anchoring mechanism;

FIG. 11 is a plan view of a retaining member;

FIG. 12 is a plan view of the retaining member of FIG. 11, in an openposition;

FIG. 13 is a plan view of the retaining clip of FIG. 11, in a closedposition;

FIG. 14 is a plan view of an alternative embodiment of a retainingmember;

FIG. 15 is a sectional view of a retaining member in accordance withanother embodiment, in an open position;

FIG. 16 is a sectional view of the retaining member of FIG. 15, in anopen position;

FIG. 17 is a sectional view of two retaining members for use in theretaining member of FIG. 15;

FIG. 18 is a sectional view of the retaining member of FIG. 15 takenalong line 18-18;

FIG. 19 is a top view of another embodiment of an anchoring mechanism;

FIG. 20 is a side view of the anchoring mechanism of FIG. 19;

FIG. 21 is a sectional view of another embodiment of an implant forrepairing an annulus fibrosus, before inflation;

FIG. 22 is another sectional view of the implant of FIG. 21 taken alongline 21-21, before inflation;

FIG. 23 is a sectional of the implant of FIG. 21, after inflation;

FIG. 24 is another sectional of the implant of FIG. 21 taken along line24-24, after inflation;

FIG. 25 is a sectional view of the implant of FIG. 21, afterimplantation and inflation;

FIG. 26 is a sectional view of another embodiment of an implant forrepairing an annulus fibrosus, before inflation;

FIG. 27 is a sectional view of the implant of FIG. 23, after inflation;and

FIG. 28 is a sectional view of the implant of FIG. 23, afterimplantation and inflation.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, in which are shown exemplary but non-limiting andnon-exhaustive embodiments of the invention. These embodiments aredescribed in sufficient detail to enable those having skill in the artto practice the invention, and it is understood that other embodimentsmay be used, and other changes may be made, without departing from thespirit or scope of the invention. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of theinvention is defined only by the appended claims. In the accompanyingdrawings, like reference numerals refer to like parts throughout thevarious figures unless otherwise specified.

FIGS. 1-3 illustrate a process for preparing a spinal segment with adefect in the annulus for receiving an implant according to anembodiment of the present disclosure. Referring to FIG. 1, annulusfibrosus 100 has a defect 102 in the posterior portion 104 of annulusfibrosus 100. FIG. 1 illustrates a defect 102 with a herniated nucleuspulposus; that is nucleus pulposus 106 has extruded through the annulardefect 102, forming a disc herniation 108. While a herniated nucleuspulposus has been illustrated here, it should be understood that defect102 can be any defect such as a radial tear, a fissure, an opening orany other type of flaw in an annulus fibrosus, and includes thoseresulting from degenerative disc disease, trauma, or other conditions.

A first access cannula 110 and a second access cannula 112 are insertedthrough annulotomies in annulus fibrosus 100 to provide bilateralposterolateral percutaneous access to the disc cavity from a firstposterolateral side of annulus 100 and a second posterolateral side ofannulus 100. First and second access cannulas 110, 112 are preferablyinserted through the safe zone defined by Kambin's triangle. First andsecond access cannulas 110, 112 are spaced away from annular defect 102so that they are not immediately adjacent to defect 102. The accesscannulas 110, 112 may be inserted by using sequentially dilatingcannulas, by minimally invasive surgical approaches, or by othertechniques known to those skilled in the art. The use of sequentiallydilating cannulas to create annulotomies spreads the fibers of theannulus fibrosus without severing them. This allows the fibers to closewhen the cannulas are removed.

Referring to FIGS. 2 and 3, an initial step is to remove disc herniation108 (if present). This may be accomplished using conventional surgicaltechniques known to those skilled in the art. Next, a partial nuclectomyis performed to remove the posterior portion 114 of nucleus pulposus106, thereby leaving nucleus remnant 162. In some embodiments, thepartial nuclectomy is performed using percutaneous techniques throughfirst and second access cannulas 110, 112. This allows the controlledselective nuclectomy of the posterior nucleus, sparing the otherwisehealthy nucleus pulposus 106 and nuclear remnant 162.

The partial nuclectomy creates a cavity 116 for receiving an implant118. For clarity, cavity 116 is illustrated as a relatively large cavityin the accompanying figures; however, it should be understood that thecavity 116 is preferably a small cavity (for example, it may beapproximately 1-2 mm wide). The posterior side of cavity 116 is formedby the inner wall of annulus fibrosus 100, while the anterior side ofcavity 116 is formed by nucleus remnant 162. A physician may use asizing balloon (i.e., a highly compliant balloon) with a contrastsolution to measure the size and shape of cavity 116 while performingthe nuclectomy to help ensure cavity 116 is properly formed, and to helpdetermine the amount of curable material to be used in the implant.

Referring to FIGS. 4-5, an implant 118 is delivered to the disc cavity116 through first and second access cannulas 110, 112. As shown in FIG.4, deflated implant 118 is inserted through first access cannula 110into disc cavity 116 so that second end 122 of implant 118 extends outof first access cannula 110 and into disc cavity 116. Second end 122 ofimplant 118 is then snared or otherwise captured using tools insertedthrough second access cannula 112 using techniques known to thoseskilled in the art, and implant 118 is the pulled through disc cavity116 into the desired position. Second end 122 may have a loop of stringor another retaining member to assist in snaring second end 122 andpulling it into the distal end of the second access cannula. One or moreradiopaque markers may be provided on implant 118 to assist in placingimplant 118 at a desired location.

Implant 118 comprises an elastomeric balloon 124 extending from firstend 120 to second end 122. A first anchor 126 is coupled to first end120 of balloon 124 and a second anchor 128 is coupled to second end 122of balloon 124. First anchor 126 includes an inflation port 130 (seeFIG. 7) for inflating balloon 124. First and second anchors 126, 128 maybe formed integrally with balloon 124 or may be formed separately andthen coupled to balloon 124.

After implant 118 is placed in the desired position, an inflation stylus144 which is inserted into inflation port 130 is used to deliverinflation material 132 to inflate balloon 124. Preferably, inflationstylus 144 is inserted into inflation port 130 before delivery throughthe catheter (i.e., it is pre-assembled, as shown in FIG. 7). In someembodiments, inflation material 132 is a curable silicone material.Inflated balloon 118 entirely fills cavity 116 so that it pressesagainst the inner wall of annulus fibrosus 100, against the posteriorside of nucleus remnant 162, and against the superior and inferiorendplates. Preferably, the inflation takes place under observation(e.g., fluoroscopy), so that the balloon 124 may be inflated in anamount and pressure sufficient to substantially restore normalintradiscal pressure, normal disc height (i.e., the distance betweenadjacent vertebral endplates) and angulation, and normal biomechanicalfunction. A second inflation port (not shown) may be utilized forinflating gas into a second balloon chamber (which is described infurther detail below).

The implant 118 presses against and forms a substantially fluid tightseal with the inner wall of annulus fibrosus 100 to reinforce theposterior annulus fibrosus 100. If a defect 102 is present, implant 118closes the defect 102. Preferably, implant 118 stretches acrosssubstantially all of the posterior portion of the annulus fibrous sothat implant 188 reinforces the entire posterior of annulus fibrosus100. This helps to reduce the risk of recurrent disc herniation. Sealingthe nuclear space helps preserve intradiscal pressure and minimizeseepage of nucleus pulposus breakdown products through the annular tearor defect, which can cause patient discomfort.

After inflation material 132 is cured, first and second access cannulas110, 112 are removed, and as shown in FIG. 6, first and second anchors126, 128, are anchored to first and second openings (or annulotomies)134, 136 formed by the first and second access cannulas 110, 112. Whenannulotomies 134, 136 are formed by spreading the fibers of annulusfibrosus 100, the fibers tighten and contract when cannulas 110, 112 areremoved due to the elasticity of the fibers of annulus fibrosus 100, andthereby engage first and second ends 120, 122 of balloon 124. Thewidening of the disc space (i.e., the restoration of normal disc height)contributes to the tightening of the fibers of annulus fibrosus 100.This fixates ends 120, 122 to annulus fibrosus 100 on opposite sides ofdefect 102 at annulotomies 134, 136 which are spaced away from defect102 towards the lateral sides of annulus 100. Furthermore, in the caseof a herniated nucleus pulposus, anchors 126, 128 are spaced away fromthe surgical site used to remove disc herniation 108. Anchors 126, and128 help reduce the risk of implant 118 from being expelled from disccavity 116 or migrating within disc cavity 116.

Referring to FIGS. 8-10, first anchor 126 and second anchor 128 may haveadditional features to minimize the possibility of the anchors beingpulled through annulus fibrosus 100. First anchor 126 may comprise acylindrical stem portion 142 with a flange 140. During insertion,cylindrical stem portion 142 is stretched over inflation stylus 144 toopen inflation port 130 to allow curable material to flow into balloon124. When inflation stylus 144 is retracted, cylindrical stem portion142 collapses to act as a valve to close inflation port 130 to sealballoon 124 and prevent inflation material 132 from escaping balloon124. The inflation stylus and stem portion 142 may have features toprevent inadvertent disconnection or leakage (such as an enlargeddischarge end or corresponding groove and slot features). Flange 140 iscompressed by the delivery cannula and access cannula 110 duringdelivery. Upon removal of inflation stylus 144 and access cannula 110,flange 140 expands to form an expanded portion 146 which help preventcylindrical stem portion 142 from being pulled through annulus fibrosus100.

Referring to FIGS. 10-14, second anchor 128 is coupled to second end 122of balloon 124. Second anchor 128 may be a cylinder or any othersuitable shape. Second anchor 128 is delivered through the disc space116 and into the distal end of the second cannula. Second anchor 128 mayhave a flange or expanded portion such as first anchor 126.Alternatively, second anchor 128 may use a different anchoringmechanism. In one embodiment, second anchor 128 comprises a loop ofmaterial with first and second sides 170, 172 which can be formed of asurgical suture material. A physician may snare the loop and use theloop to pull the second anchor into the second cannula during theimplantation procedure. A retaining member (or clip) 174 can be attachedto the strings and drawn tight against annulus fibrosus 100 to help holdsecond anchor 128 in place. In some embodiments, retaining member 174comprises a first member 176 with a sliding plate 178 slidably connectedto it. First member 176 has at least one and preferably two apertures180. Sliding plate 178 has at least one and preferably two apertures182. A biasing member 184 biases sliding plate 178 outwardly (as shownin FIG. 13). When sliding plate 178 is squeezed close, apertures 180 and182 are aligned, and first and second sides 170, 172 of the loop ofsurgical suture material can be placed through the apertures. A usermust cut the loop into two separate strings 170, 172 so that they can beplaced through the apertures. When released, plate 178 is biased outwardso that strings 170, 172 are trapped by apertures 180, 182 (see FIG.12). A user may slide retaining member 174 down strings 170, 172 untilit is tight against the outer margin of annulus fibrosus 100. In someembodiments, the outer diameter of retaining member 174 in the openposition is substantially the same size as the inner diameter of secondaccess cannula 112 so that sliding plate 178 is held into the openposition until it exits the distal end of second access cannula 112.Although two strings are shown in the illustrated embodiment, any numberof strings may be used, from one or more. Similarly, retaining memberswith a different number of sliding plates may be used, as shown in FIG.14, which illustrates a retaining member 190 with two sliding plates192.

FIGS. 15-20 illustrate another embodiment of a retaining member and ananchoring mechanism. Retaining member 194 comprises an outer retainingring 196 with first and second opening 198, 200 for receiving first andsecond sliding members 202, 204, respectively. First and second slidingmembers 202, and 204 slide in and out (i.e., toward and away from thecenter of retaining ring 198), and are biased outward by biasing memberssuch as springs (which are not illustrated for clarity). The outerdiameter of retaining ring 196 is substantially the same as the innerdiameter of a delivery cannula 206. First and second sliding members202, 204 are held in the open position (i.e., squeezed together so thatslot 208 is open) by the delivery cannula 206. Sliding members 202, 204are preferably the same shape and configuration. Each sliding membercomprises a flat member 210 with a protruding u-shaped member 212 whichforms an aperture 214. A tongue 216 extends from u-shaped member 212.The u-shaped member 212 is offset from the centerline of the flat member210 so that the sliding members have be inserted into retaining ring 196in different orientations. This way, u-shaped members 212 formcomplementary sliding members (referring to FIG. 18) and do notinterfere with one another when placed in the open position. Retainingmember 194 may be formed of any biocompatible material, such asstainless steel or polymeric material.

To use retaining member 194, the sliding plates are squeezed together sothat apertures 214 of the two plates are aligned and form slot 208.String 170, 172 are placed through slot 208, and slot 208 is loaded intocannula 206. Retaining member 194 is then delivered down deliverycannula 206 by a pusher (not illustrated) until it is adjacent thesecond anchor 216. The pusher can be a cannula with an outer diameterwhich fits snugly within delivery cannula 206. While holding retainingmember 194 firmly against second anchor 218, the delivery cannula isremoved, allowing the biasing members to close sliding members 202, 204(i.e., press the sliding members outward to close slot 208, as shown inFIGS. 16 and 18). In some embodiments, retaining ring 196 and slidingplates 202, 204 may have locking features to lock the sliding plates inthe closed position once the retaining member 194 is in place. Oncesliding plates 202, 204 expand outward from retaining ring 196, theyform an enlarged portion which helps anchor the end of the implant andprevent the anchor from being pulled through the annulus fibrosus.

FIGS. 19 and 20 illustrate an anchor 218 which is particularly suitablefor use with the retaining member of FIGS. 15-18. Anchor 218 comprises acylindrical member 220 with an embedded loop of wire or string 222. Loop222 is preferably formed of a material which retains its shape, such aswire or stiff nylon. Loop 222 can be used to snare anchor 218 and pullit into the proper position within the distal segment of the secondcannula, as described previously. Preferably, loop 222 is long enoughthat it can be pulled out the end of second delivery cannula 212,although it is shown shorter in the illustrations for clarity. A secondanchoring loop 224 is placed near the anchor and fastened to loop 222.When anchor 218 is used with retaining member 194, the tongues 216extend into anchoring loop 224 when tongues 216 are closed to form apositive connection. Thus, instead of relying solely on friction betweenloop 222 and sliding plates 202, 204, anchoring loop 224 is positivelylocked to retaining member 194.

Referring to FIGS. 21-25, in some embodiments balloon 124 of implant 118may comprise a multi-layered balloon. For example, balloon 124 may havea reinforcement layer 150 on the posterior portion 156 of the implant118 to strengthen the implant and aid incorporation of the implant 118into the annulus fibrosus. Reinforcement layer 150 may be located on theinterior or exterior of balloon 124. Reinforcement layer 150 may be anybiocompatible material with a high strength, such as a woven, knitted orbraided textile or an ePTFE material. Other fiber deposition techniquessuch as electrospinning may be used to form reinforcement layer 150.After balloon 124 is inflated and the curable material is cured, theimplant 118 comprises a flexible and resilient structure which isresistant to migration through annular defect 102.

In some embodiments, balloon 124 comprises a silicone material. In someembodiments, balloon 124 comprises a PTFE material (such as an expandedPTFE material). A layer of carbon material may be included to enhancethe bond between the PTFE material and the curable material. Theporosity of the PTFE material may be controlled to allow partialpenetration of the curable material while it is in the liquid state tocreate an integrated structure after curing which minimizes thepossibility of delamination. Balloon 124 may be porous to allow theescape of air in the system or air trapped in the liquid silicone duringmixing.

In some embodiments, balloon 124 may have differential and directionalexpandability to control the direction and amount of expansion ofballoon 124. In some embodiments, balloon 124 has segments of increasedbase and dimensional stability. In some embodiments, the surface ofballoon 124 may have a unique surface topography to enhance desiredcharacteristics. For example, the surface may have increased lubricityto reduce friction against vertebral endplate surfaces and enhancetissue in-growth in the annulus fibrosus. Balloon 124 may be formed invarious shapes to fit different cavity configurations.

In some embodiments, balloon 124 is adapted to fill an annular defect.Outer layer 150 of balloon 124 may have at least one opening 152 throughwhich inner layer 160 protrudes when the implant 118 is inflated withincavity 116. By aligning opening 152 in outer layer 150 with defect 102in annular fibrosis 100, inner layer 160 protrudes out opening 152 toform a protrusion 154. Protrusion 154 acts as a plug to fill the annulardefect 102 and the associated cavity, which assists in treating annulardefect 102. In some embodiments, inner layer 160 of balloon 124comprises a compliant material, such as a silicone membrane; and outerlayer 150 comprises a material which is less compliant than inner layer160. In some embodiments, outer layer 150 is fiber reinforced. Theopening 152 in less compliant outer layer 150 allows compliant innerlayer 160 to expand therethrough.

In some embodiments, anterior wall 158 of balloon 124 is relativelythinner or more compliant than posterior wall 156 of balloon 124. Asballoon 124 expands, differential expansion occurs with more compliantanterior wall 158 expanding more than that of posterior wall 156. Insome embodiments, less compliant posterior wall 156 comprises one ormore layers of a matrix of spun fibers. Multi-layered designs may beconfigured to strengthen or otherwise affect certain properties of theballoon, including mechanical properties such as burst strength andpuncture resistance.

Use of multilayered and differential balloon walls may facilitatevarious aspects of manufacturing, deployment and therapies involvingnuclear implants. For example, as discussed above, a multi-layereddesign may be thinner and/or more compliant along its anterior wall 156.This may enable implant balloon 124 to be folded or otherwise packedinto a smaller delivery configuration. Additionally, smaller profilesmay require access cannulas having a smaller diameter and smallerannulotomy puncture, which decreases the possibility of implantextrusion.

Posterior wall 156 of a multilayer nuclear implant balloon 124 may beformed of multiple layers of the same material, or multiple layers ofdifferent materials. In some embodiments, layers may be formed ofmaterials with similar compliance, providing an additive effect. Inother embodiments, layers may be formed of different materials andformed independently, allowing for properties of each layer to beindividually optimized.

Balloon 124 may be designed to expand symmetrically or asymmetrically.The balloon wall may comprise at least one radially asymmetricallydilatable portion, wherein the cross-section has one or more regionsthat differ in terms of compliance, strength and other characteristics.Such balloons provide enhanced performance though use of differentialand directional expandability of the implant increased dimensionalstability, improved cavity contour and improved tissue incorporation.

In some embodiments, balloon 124 has areas of electrospun polymericmaterial in combination with a silicone material, and other areas ofuncovered silicone material. The electrospun polymeric material maycomprise expanded PTFE (ePTFE). Application of PTFE to posterior wall156 of implant 118 at least partially constrains inflation along theinner annulus and provides enhanced performance through use ofdifferential and direction expandability. Furthermore, PTFE enhancessoft tissue purchase by encouraging fibrocyte migration andincorporation of the implant with the posterior annulus. This helpsguard against further disc herniation.

Balloon 124 may comprise flexible materials which accommodate alow-profile delivery without compromising strength and elasticity. Insome embodiments, balloon 124 comprises an ultra-high molecular weightpolyethylene (UHMwPE) material, such as DYNEEMA®, available from RoyalDSM of Herleen, Netherlands. In some embodiments, balloon 124 may becoated with a hydrophilic material to increase lubricity.

In some embodiments, anterior wall 158 is relativity thinner and morecompliant than posterior wall 156 so that it expands more than posteriorwall 156, sequestering the remaining portion of nucleus pulposus 106 andproviding disc space widening and angle restoration.

In one embodiment the posterior portion of the nuclear implant consistsof a flexible tubular three-dimensionally braided structure of metal orpolymeric monofilaments, and polymeric multifilament yarns. The metallicthread elements or strands are favored for applications requiringadditional reinforcement and effective protection against migration ofthe implant through a large annulus defect or a very weakened posteriorannulus.

Referring to FIGS. 26-28, in some embodiments, an implant 230 for apartial nuclectomy comprises a proximal anchor 232, a distal anchor 234,and an inflatable balloon 236 extending therebetween. The inflatableballoon 236 is a multi-chambered balloon, having at least a firstchamber 238 and a second chamber 240. In one embodiment, second chamber240 is disposed inside first chamber 238 and is completely surrounded byfirst chamber 238. The inner and outer chamber may be filled withdifferent materials to provide implant 230 with desired characteristics.It should be understood to one of ordinary skill in the art that anydevice, apparatus and/or system suitable for injecting fluid can be usedto inflate first and second chambers 238, 240. In some embodiments,first chamber 238 is filled with a curable elastomeric material 242,while second chamber 240 is filled with a compressible material 244(i.e., a gaseous material). This allows the implant 230 to absorb suddenincreases in intra-discal pressure, acting effectively as a shockabsorber. Like the other embodiments, the balloon 236 can comprisemultiple layers, and a reinforcing layer 246 can be provided.

The above specification and examples provide a complete description ofthe structure and use of exemplary embodiments. Although certainembodiments have been described above with a certain degree ofparticularity, or with reference to one or more individual embodiments,those skilled in the art could make numerous alterations to thedisclosed embodiments without departing from the scope of thisinvention. As such, the various illustrative embodiments of the presentdevices are not intended to be limited to the particular formsdisclosed. Rather, they include all modifications and alternativesfalling within the scope of the claims, and embodiments other than theone shown may include some or all of the features of the depictedembodiment. For example, components may be combined as a unitarystructure, and/or connections may be substituted. Further, whereappropriate, aspects of any of the examples described above may becombined with aspects of any of the other examples described to formfurther examples having comparable or different properties andaddressing the same or different problems. Similarly, it will beunderstood that the benefits and advantages described above may relateto one embodiment or may relate to several embodiments.

The claims are not intended to include, and should not be interpreted toinclude, means-plus- or step-plus-function limitations, unless such alimitation is explicitly recited in a given claim using the phrase(s)“means for” or “step for,” respectively

What is claimed is:
 1. A method of reinforcing a posterior annulusfibrosus, comprising: inserting first and second cannulas through firstand second annulotomies located on first and second sides of theposterior annulus fibrosus to spread fibers of the annulus fibrosus togain access to a nuclear space; performing a subtotal nuclectomy tocreate a cavity extending between the first and second cannula, whereina posterior side of the cavity is formed by the annulus fibrosus and theanterior side of the cavity is formed by a nucleus remnant; inserting aninflatable implant through the first cannula into the cavity formed bythe subtotal nuclectomy to position the inflatable implant toward thesecond cannula so that a first end of the inflatable implant is locatedat the first annulotomy and a second end of the inflatable implant islocated at the second annulotomy, wherein an anterior portion of theinflatable implant is more compliant than a portion of the inflatableimplant; expanding the inflatable implant with a curable medium so thatthe inflatable implant substantially fills the cavity and pressesagainst the annulus fibrosus to form a substantially fluid tight sealwith the annulus fibrosus; anchoring the first end of the inflatableimplant to the first annulotomy; and anchoring the second end of theinflatable implant to the second annulotomy.
 2. The method of claim 1,wherein the posterior portion of the annulus fibrosus has a defect, andthe first and second annulotomies are spaced away from the defect onfirst and second sides of the defect.
 3. The method of claim 1, whereinthe first and second annulotomies are on the posterolateral sides of theannulus fibrosus.
 4. The method of claim 1, wherein the steps ofanchoring the first and second ends of the implant to the first andsecond annulutomies comprises removing the first and second cannulas sothat the first and second annulotomies engage the first and second endsof the implant.
 5. The method of claim 1, wherein the step of insertingthe inflatable implant into the cavity comprises deploying the implantinto the cavity through the first cannula.
 6. The method of claim 5,wherein the step of inserting the inflatable implant into the cavityfurther comprises snaring the second end of the implant through thesecond cannula and maneuvering the implant into position.
 7. The methodof claim 1, wherein the step of anchoring the second end of the implantcomprises attaching a retaining member to the second end of the implant,wherein the retaining member is larger than the second annulotomy. 8.The method of claim 1, wherein the step of expanding the implant furthercomprises inflating an interior chamber with a gaseous medium.
 9. Amethod of reinforcing a posterior annulus fibrosus, comprising:accessing, by spreading fibers of the annulus fibrosus, a nuclear spaceformed by the annulus fibrosus; performing a partial nuclectomy tocreate a cavity extending from a first lateral side of the annulusfibrosus to a second lateral side of the annulus fibrosus, wherein aposterior side of the cavity is formed by an inner wall of the annulusfibrosus and an anterior side of the cavity is formed by a nucleusremnant; inserting an inflatable balloon with a first end and a secondend into the cavity formed by the partial nuclectomy wherein an anteriorportion of the inflatable balloon is more compliant than a portion ofthe inflatable baloon; inflating the inflatable balloon with a curablemedium; anchoring the first end of the inflatable balloon to the annulusfibrosus on the first lateral side of the annulus fibrosus; andanchoring the second end of the inflatable balloon to the annulusfibrosus on the second lateral side of the annulus fibrosus.
 10. Themethod of claim 9, wherein the step of accessing the nuclear spacecomprises obtaining bilateral posterolateral percutaneous access withfirst and second cannulas inserted through first and second annulotomiesat the first and second sides of the annulus fibrosus.
 11. The method ofclaim 10, wherein the inflatable balloon extends from the first cannulato the second cannula.
 12. The method of claim 11, further comprisingwithdrawing the first and second cannulas so that the first and secondannulotomies engage the first and second ends of the balloon to anchorthe first and second ends of the balloon to the annulus fibrosus. 13.The method of claim 10, wherein the inflatable balloon is insertedthrough the first cannula into the cavity.
 14. The method of claim 13,further comprising snaring the balloon through the second cannula andmaneuvering the balloon into position.
 15. The method of claim 9,further comprises: aligning a portion of the inflatable balloon which isadapted to protrude from the inflatable balloon with an annular defect,and; inflating the inflatable balloon so that the balloon protrudes intothe annular defect.
 16. The method of claim 15, wherein the annulardefect comprises a defect caused by one of a herniated nucleus pulposusor an iatrogenic defect.
 17. The method of claim 9, wherein the balloonforms a substantially fluid tight seal with the annulus fibrosus.